1. Field of the Invention
This invention relates to water-insoluble polyvinylpyrrolidone (PVP)-iodine, and, more particularly, to a process for preparing such product as a stable, uniform, free-flowing powder.
2. Description of the Prior Art
Grosser, in U.S. Pat. No. 3,136,755, disclosed a process for preparing water-insoluble PVP-iodine complexes by heating water-insoluble PVP and iodine at about 90.degree. C. for 24 hours. The product contains only 8.8% available iodine. However, the product has a very low available iodine content, is quite unstable, and does not provide a uniform, free-flowing powder.
Field et al. in U.S. Pat. No. 3,907,720 described a process for making water-insoluble PVP-iodine complexes crosslinked with a suitable crosslinking agent in the form of porous beads or granules by reacting PVP in the form of porous beads or granules with iodine or a solution of iodine at a temperature ranging from room temperature to about 100.degree. C. or more, over a fairly prolonged period of time, i.e. from about 2 hours to 2 weeks or longer. The process, however, did not afford a stable, uniform, free-flowing powder having a high available iodine content.
Other U.S. Pat. Nos. of interest are 4,402,937; 4,027,083; 4,200,710; 4,320,114; 4,035,049; 2,900,305; and 2,754,245.